Liquid crystal display device and method for driving display device

- Sharp Kabushiki Kaisha

A method for driving a simple matrix type display device includes the steps of: applying a data voltage corresponding to values obtained by an orthogonal transform of input data to the data electrodes; applying a scanning voltage to the scanning electrodes, the scanning voltage corresponding to an orthogonal function used for the orthogonal transform; and reproducing the input data by an orthogonal inverse transform of the data voltage on the display panel, wherein the step of applying the scanning voltage includes the steps of: applying a scanning selection pulse signal having at least two levels to the scanning electrodes as a scanning voltage; and fixing the scanning selection pulse signal to an unselected level during a first period, a second period, or both of the first and second periods, the first period being defined as a period from the beginning of the data output until a predetermined time later in a data voltage output period, and the second period being defined as a period from a predetermined short time before the completion of the data output until the completion of the data output in the data voltage output period.

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Claims

1. A method for driving a simple matrix type display device including a display panel having a plurality of scanning electrodes and a plurality of data electrodes intersecting each other, and a matrix of pixels located at the respective intersections of the plurality of scanning electrodes and the plurality of data electrodes, the method comprising the steps of:

applying a data voltage to the plurality of data electrodes, the data voltage corresponding to values obtained by performing an orthogonal transform of input data;
applying a scanning voltage to the scanning electrodes, the scanning voltage corresponding to an orthogonal function used for the orthogonal transform; and
reproducing the input data by performing an orthogonal inverse transform of the data voltage on the display panel,
wherein the step of applying the scanning voltage includes the steps of:
applying a scanning selection pulse signal which has at least two levels to the plurality of scanning electrodes as a scanning voltage; and
fixing the scanning selection pulse signal to an unselected level during a first period, a second period, or both of the first and second periods,
the first period being defined as a period from the beginning of the output of the data until a predetermined time later in a data voltage output period during which the data voltage is output to each of the data electrodes, and
the second period being defined as a period from a predetermined short time before the completion of the output of data until the completion of the output of data in the data voltage output period.

2. A liquid crystal display device comprising:

a display panel having a plurality of scanning electrodes and a plurality of data electrodes intersecting each other and a matrix of pixels located at the respective intersections of the plurality of scanning electrodes and the plurality of data electrodes;
a data driver for applying a data voltage to the plurality of data electrodes, the data voltage corresponding to values obtained by performing an orthogonal transform of input data;
a scanning driver for applying a scanning voltage to the plurality of scanning electrodes, the scanning voltage corresponding to an orthogonal function used for the orthogonal transform; and
a timing control circuit for receiving a synchronization signal which defines timing of outputting the data voltage from the data driver and for outputting a control signal which fixes the potential level of the scanning electrode at an unselected level during a first period, a second period, or both of the first and second periods,
the first period being defined as a period from the beginning of the output of data until a predetermined time later in a data voltage output period which is determined by the synchronization signal, and
the second period being defined as a period from a predetermined short time before the completion of the output of data until the completion of the output of data in the data voltage output period,
wherein the control signal output from the timing control circuit controls the scanning driver to output a scanning selection pulse during each data voltage output period so that a pulse width of the scanning selection pulse is shorter than the data voltage output period.

3. A liquid crystal display device according to claim 2,

wherein the scanning selection pulse has at least two selected levels and the unselected level, and
the scanning driver outputs one of the levels of the scanning selection pulse based on the orthogonal function used for the orthogonal transform, in accordance with the output timing of the corresponding data voltage from the data driver, and
the scanning driver fixes the currently output scanning selection pulse to the unselected level, based on the control signal from the timing control circuit and independently of the outputting of the scanning selection pulses.

4. The method of claim 1, wherein the first period is in a range of 10% to 20% of the data voltage output period.

5. The method of claim 1, wherein the second period is in a range of 10% to 20% of the data voltage output period.

6. The method of claim 1, further comprising adjusting a level of the scanning voltage to compensate for the first period.

7. The method of claim 1, further comprising adjusting a level of the data voltage to compensate for the first period.

8. The method of claim 1, further comprising adjusting a level of the scanning voltage to compensate for the second period.

9. The method of claim 1, further comprising adjusting a level of the data voltage to compensate for the second period.

10. The method of claim 1, wherein the method is a multiline selection (MLS) method.

11. A liquid crystal display device according of claim 2, wherein the first period is in a range of 10% to 20% of the data voltage output period.

12. A liquid crystal display device according of claim 2, wherein the second period is in a range of 10% to 20% of the data voltage output period.

13. A liquid crystal display device according of claim 2, further comprising adjusting a level of the scanning voltage to compensate for the first period.

14. A liquid crystal display device according of claim 2, further comprising adjusting a level of the data voltage to compensate for the first period.

15. A liquid crystal display device according of claim 2, further comprising adjusting a level of the scanning voltage to compensate for the second period.

16. A liquid crystal display device according of claim 2, further comprising adjusting a level of the data voltage to compensate for the second period.

17. A liquid crystal display device according of claim 2, wherein the liquid crystal display device is driven by a multiline selection (MLS) method.

Referenced Cited
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Other references
  • Nehring et al, "Ultimate Limits for Matrix Addressing of RMS-Responding Liquid-Crystal Displays", IEEE Transactions on Electron Devices, vol. ED-26, No. 5, May 1979, pp. 795-802. Ruckmongathan, "Addressing Techniques for RMS Responding LCDs-A Review", Japan Display '92, pp. 77-80, 1992. Kudo et al, "Study on Driving Methods for Fast-Responding STN-LSDs" Technical Report of IEICE, EID94-129, ED94-157, SDM94-186, pp. 13-18, 1995. Scheffer et al, "13/4: Active Addressing Method for High-Contrast Video-Rate STN Displays", SID 92 Digest, pp. 228-231, 1992. Ruckmongathan et al, "S3-4 A New Addressing Technique for Fast Responding STN LCDs", Japan Display '92, pp. 65-68, 1992. Ruckmongathan, "A Generalized Addressing Technique for RMS Responding Matrix LCDs", 1988 International Display Research Conference, pp. 80-85, 1988.
Patent History
Patent number: 5870070
Type: Grant
Filed: Oct 3, 1996
Date of Patent: Feb 9, 1999
Assignee: Sharp Kabushiki Kaisha (Osaka)
Inventors: Hiroyuki Furukawa (Ueno), Shinya Takahashi (Yamatokoriyama), Kunihiko Yamamoto (Kashiba)
Primary Examiner: Steven Saras
Assistant Examiner: David L. Lewis
Law Firm: Nixon & Vanderhye, P.C.
Application Number: 8/725,395
Classifications
Current U.S. Class: Particular Timing Circuit (345/99); Particular Row Or Column Control (e.g., Shift Register) (345/100)
International Classification: G09G 336;